Parkinson's disease (PD) is the second most common neurodegenerative disease and the severity of PD still progress during the ensuing years. Currently, there is no promising medical or surgical treatment to abrogate the disease deterioration. Granulocyte colony-stimulating factor (G-CSF), one of hematopoietic growth factors, has been routinely used for hematologic disorders and stem cell harvest from normal subject. G-CSF also demonstrated neuroprotection for rodents PD model. We hypothesize G-CSF will exert the effectiveness of neuroprotection for PD patients.